Private Pilot Private Exam

What does a positive indication on an ammeter signify?

1. The battery is discharging

2. The battery is fully drained

3. The rate of charge on the battery

4. The alternator is malfunctioning

The correct answer is: The rate of charge on the battery

A positive indication on an ammeter signifies the rate of charge on the battery. In a typical aircraft electrical system, the ammeter measures the flow of electric current to and from the battery. When the ammeter shows a positive reading, it indicates that the alternator is supplying more current than the battery is consuming. This means that the battery is receiving a charge, which is crucial for ensuring that it remains operational and fully charged for when it is needed. Understanding this function is essential because it helps pilots monitor the health of the electrical system. If the ammeter shows a negative reading, that would indicate the battery is discharging, which could lead to potential issues if sustained for a long period, while a reading of zero would suggest a balance between current being supplied and consumed.